Abstract: An arrangement for converting an AC supply to a DC supply comprising an inverter circuit and a boost power factor correction stage. The inverter circuit comprises switchable components and utilizes a pulsed waveform indicative of power factor correction for causing some at least of the components repeatedly to adopt a condition permitting the boost power factor correction stage to draw current from the AC supply.

Abstract: A resonant inverter has transistor switches (20, 30) arranged to conduct current from a d.c. source (10) alternately in one direction and the other through an inductor (40) and capacitor (42). The transistor switches (20, 30) are turned on alternately by signals from secondary windings (24, 34) of a drive transformer (44) having a primary winding (45) in series with the inductor (40) and capacitor (42). To control the output power of the inverter, a control circuit (50) senses reversal of current in through the inductor (40) and capacitor (42) and turns off one of the transistor switches (30 ) a predetermined time after current reversal. Current reversal is sensed by an additional transformer (60) having a primary winding (61) in series with the inductor (40) and capacitor (42). The control circuit (50) includes a timer (52) controlling the predetermined time, which may be varied to vary the power output of the inverter. A load (80) is connected across the inductor (40 ) or capacitor (42 ) .

Abstract: The power supply circuit has an inductor connected to a DC source through a regulating circuit arranged to maintain a constant current in the inductor. A MOSFET is connected to the inductor and to the spark gap so that when the MOSFET is conducting, current is diverted from the inductor to the spark gap. The frequency and mark-space ratio of switching of the switching device is controlled to control the machining process. A second switching device (40) is arranged to conduct when the voltage across a capacitor (34) exceeds a reference voltage. A diode (46) is used to return excess energy to the DC source.

Abstract: An alternator for an internal combustion engine driven vehicle comprises a permanent magnet rotor mounted in operation for rotation with the engine crankshaft, a wound stator within which the rotor extends, rectifying means connected to the output of the stator, and a pulse controlled DC chopper regulator supplied from the output of the rectifier means and adapted to control the output from the rectifier and to supply the so controlled output to the vehicle battery for charging thereof.